Definition
A backlink is a reference from an external domain to your page. Search engines read it as an endorsement: when credible sites link to a piece of content, it's treated as more trustworthy. Backlinks have been one of the strongest external ranking pillars of classic search since Google's earliest days.
Quality is decisive, not volume. A link from a topically relevant, high-authority site outweighs a hundred from link farms - which are now actively penalised. Bought or manipulative links are a risk, not a lever; sustainable building comes from citable content, PR and real relationships.
Important context for the AI era: for visibility in AI answer systems, plain brand mentions (on Reddit, YouTube, Wikipedia, LinkedIn) now correlate about three times more strongly than backlink-based domain authority (Ahrefs, 2025). Backlinks remain relevant for classic ranking - but for GEO, the unlinked mention of the brand name is often more valuable.
Why it matters
Backlinks from credible domains are a signal you can't generate on your own site - which is why search engines weight them. For AI citations, however, the bare brand mention spread across the web counts even more.
In practice
- 01A link from a trade publication or university weighs more than ten from random blogs.
- 02A brand mention in a frequently cited Reddit thread can lift AI visibility more than an extra backlink.
- 03Link farms and bought bulk links now lead to penalties rather than lift.
